To gain a comprehensive understanding of cellular structures and function, correlative light and electron microscopy has been widely utilized to facilitate the acquisition of both macroscopic view of the whole organism and the localization of single molecules or macromolecular complexes. However, current correlative microscopy solutions require extensive sample preparation before biological specimens can be investigated using EM, which potentially altering the relevant structures and inducing image artifacts. Therefore, this project is aimed to develop a universal continuous-flow environmental specimen holder system for the light microscope (LM), the scanning and transmission electron microscope (SEM and TEM) with biofunctionable sample substrate and micron- precision location reference system for correlative microscopy to take advantage of multiple imaging modalities spanning a range of spatial scales and frequencies. This powerful and versatile correlative microscopy specimen holder platform enables environmental LM and EM, accurate temperature regulation (20:C to 80:C), and empowers microfluidic experiments being conducted inside the chamber, where biological samples are incubated or drug treated. It also allows sample imaging across LM, SEM and TEM platforms without additional manipulation. The proposed cross- correlated specimen holder platform offers the capability to transform any existing individual microscopes into the most complete correlative microscopy system that permits the entire microscopy field joining forces to not only uncover a great deal of insights and research the most urgent advances in modern medicine, but more importantly open new doors and opportunities to the entire life and health sciences. PUBLIC HEALTH RELEVANCE: An Integrated Cross-Correlative Environmental Specimen Holder Platform for Optical, Scanning and Transmission Electron Microscopes Relevance The environmental cross-correlative light and electron microscopy characterization techniques that will be developed in this project will have a direct impact on the understanding of biological processes. It targets the cross-correlative nanometer-scale imaging of biological structures in their native liquid environment, as well as the ability to observe biological processes with high resolution as they are occurring. This new correlative approach, which represents a giant leap forward compared to current correlative microscopy techniques using cryogenic freezing, will be used to gain a comprehensive understanding of cellular structures and function.